1. Field of the Invention
This invention relates generally to a system for providing vehicle lateral stability control and, more particularly, to a system for providing vehicle lateral stability control that integrates vehicle dynamics control from sensor measurements and target path projections, and path tracking control that integrates vehicle kinematics control with vehicle dynamics control.
2. Discussion of the Related Art
Vehicle dynamics typically refers to the yaw, side-slip and roll of a vehicle and vehicle kinematics typically refers to vehicle path and lane tracking. Vehicle stability control systems are known in the art for providing stability control based on vehicle dynamics. Further, lane keeping and/or lane tracking systems are known that use vehicle kinematics. If the vehicle is traveling along a curve where the road surface has a low coefficient of friction because of ice or snow, vehicle dynamics and kinematics are both important. Conventionally, vehicle dynamics and kinematics control were performed separately and independently although they may be coordinated by a supervisory control, but only to an extent that they do not interfere with each other.
A typical vehicle stability control system relies solely on the driver steering input to generate a control command for steering assist and/or differential braking. However, driver response and style vary greatly, and there is no reliable way to identify the driving skill level and the driving style to determine how the driver is handling a particular driving situation. Contributing factors include driver incapacity, lack of experience, panic situation, etc.
Further, during a path tracking maneuver, the vehicle may encounter stability problems because of sensor data quality, such as noise, slow through-put and possible environmental disturbances. Also, because the road surface condition is unknown, and typically is not considered for path-tracking control, the same control design for a high coefficient of friction surface may generate a significant vehicle oscillation or even instability for a vehicle traveling on a low coefficient of friction surface.